This invention relates generally to releasably attachable accessory devices for use in enhancing the operation of electronic apparatus and more particularly to accessory control devices that operate upon being added to various kinds of electronic apparatus and, upon installation of the accessory control device in such electronic apparatus, enhancing information handling, processing and executing of functions in such electronic apparatus. More specifically, this invention relates to accessory control devices of the type for use in conjunction with electronic apparatus which are installed in an input connector of the apparatus wherein the inlet connector was initially adapted for read only data capability from inserted accessory control devices into the input connector. However, the accessory control devices of this invention are enhanced to have intelligence to provide the capability of efficiently handling and processing information of the information processing means of the electronic apparatus when inserted into the input connector of the electronic apparatus.
In recent years, personal computers, word processors, workstations and other electronic apparatus operating under digital logic control, and printers, facsimile machines, electronic pocketbooks, electronic musical instruments, electronic cooking appliances, electronic cameras and other electronic apparatus operating under microprocessor control are being employed in all areas of society. Further, the use of microprocessors is spreading rapidly to applications, such as, in automobiles, robotics and machine controlled tools, as well as all other types of electric products. Such apparatus utilizing digital logic operation and software have the potential of flexible control as compared with simple feedback control realized only with hardware, and, further, have the advantage of being able to change essential functions or change to different functions or to upgrade existing functions through changes to their software. Therefore, it is possible to accomplish completely different control utilizing the same hardware by, for example, merely changing the contents of the ROM utilized in conjunction with the microprocessor wherein procedures are stored or loading of a new program to the main memory from an external device, such as, a floppy disk is readily accomplished. As used herein, "procedures" is meant to be interchangeable with programs, instruction set, processing, process, instructions, program control, commands and the like.
However, since the throughput of the processor that actually performs control is dependent on the hardware, e.g., a predetermined number of operations per unit time, the number of bits that can be handled at one time and width of the bus that performs data transfer, improvement by upgrading the software is limited to only improved usage. As a result, any significant improvement in the performance of the existing electronic apparatus cannot, therefore, be realistically accomplished since it is limited by the existing hardware of the electronic apparatus. Further, upgrading by changing the software requires replacement of the ROM if the software is fused into the ROM, thus making it difficult to achieve in many cases. Therefore, upgrading the software is difficult in most cases except those in which ROM replacement is designed into the device from the beginning or the software is supplied on a replaceable medium, such as, by means of a floppy disk.
In personal computers, for example, accelerators on accelerator boards mounted in the computer housing are employed to improve the functionality of the computer system by completely replacing the microprocessor. However, this requires replacement of the CPU on the motherboard or other difficult operations that cannot generally be performed by ordinary computer users.
Generally, in the past, no consideration has been made regarding the improvement or changing of the functionality of existing printers, facsimile machines, electronic pocketbooks, electronic musical instruments, electronic cooking appliances, electronic cameras and other consumer electronic apparatus containing a microprocessor, and, further, existing electrical equipment for automobiles, robots, machine tools and other industrial electronic apparatus as well as all types of electric appliances. This lack of consideration is now described in conjunction with respect to one particular electronic apparatus, to wit, a page printer, although it should be realized that its is not limited to this particular kind of electronic apparatus.
In recent years, the rapid development and distribution of laser printers and other page printers has become widespread with high speed output in the transfer of data from computers to such printers for printing. In the case of laser printers, their resolutions range from 240 to 800 dots per inch (DPI), and these printers are capable of printing several pages a minute. One class of these printers generally employ a xerographic unit that employs a photosensitive medium, e.g., a xerographic drum, as the print engine. Since such a print engine continuously performs each of the functions of medium charging, exposure, toner application and image transfer processes in sync with the rotation of the photosensitive drum, the printing processing immediately begins after a image for a first single page has been processed and is stored in the printer memory. As a result, the memory provided in page printers for image processing must have the capacity to hold an image for at least one page. If compression of image data is not performed, the capacity is determined by the resolution and the size of the paper that is capable of being processed. For example, in the case of a resolution of 300 DPI and a paper size of 8 inches by 10 inches, 7,200,000 (8.times.10.times.300.times.300) dots must be manipulated and at least a 0.9 megabyte memory is required to hold this page of data.
In printers that function to receive character codes, row and column pitch and other information as print data and expand this data into an image, or in printers that receive a program described by a page description language and then expand the image by interpretation of the page description, it is necessary to calculate and produce a bit image based on such print data, which greatly reduces the overall processing speed compared to simple bit image transfer since there is huge volume of information to be expanded or interpreted. In other words, the processing speed of a printer is determined principally by the throughput of the printer processor that performs processing and memory access time and it is well known that their processing capability falls far short of the printing throughput and capability of the xerographic unit itself. For example, in a page printer capable of printing 10 pages per minute, only six seconds is allowed to prepare the image data for one page (0.9 megabytes of data) of printing. To process all 0.9 megabytes of data in this period of time means that the processing time allowed for one byte is a mere 6.6 microseconds (6 s/0.9 MB). This processing speed can possibly be realized with one of the high speed RISC type processors currently available on the market today. In contrast to this, however, there are currently many xerography units in use today capable of printing 10 pages per minute. Therefore, the throughput of the controllers that process print data in these printers is a bottleneck in improving overall print speeds of presently developed printers as well as existing printers being employed by end users.
For this reason, there are situations wherein the image processing throughput is remains below the throughput capability of the xerography unit utilized in laser printers. Furthermore, even if it becomes possible to obtain a processor with a high image processing throughput as the microprocessor technology continually advances, it is impossible to improve image processing functionality later in these printers already in the hands of end users.
There are some page printers whose functionality can be improved by being able to increase internal memory capacity or by providing an expansion slot and installing a cartridge with built-in fonts or programs stored in the cartridge. For example, to expand the functionality of a laser printer that supports only a specific page description language to process another page description language, the program of the other page description language interpreter is supplied in the form of an IC card or other type of cartridge. This cartridge contains the program in the form of a mask ROM and is installed in the expansion slot of the printer. However, these attempts to improve processing speed through memory expansion do not improve image processing throughput.
As a particular example, a cartridge provided in the input connector of the laser printer supplies a program of a particular page description language interpreter. The controller in the itself reads a prescribed address assigned to the cartridge in accordance with predetermined timing, such as, immediately upon power up of the printer. If the cartridge containing the page description language program has been installed, a specific code is returned so that the printer controller knows that the cartridge is the particular page description language. Through this means, control of the printer is transferred to the interpreter program in the cartridge. As a result, the printer becomes capable of interpreting data received from outside the printer environment, but the image processing speed itself is not improved. In fact, the overall printing speed may even be reduced when employing a new high level page description language.
It is an object of this invention to provide an accessory control device for an electronic apparatus that is capable of enhancing the operation of the processor of the electronic apparatus.
It is another object of this invention is an information processing device in conjunction with an electronic apparatus for use with an accessory control device to provide for overall improvement, change in or added functionality of the electronic apparatus.
It is another object of this invention to provide an accessory control device for an electronic apparatus, releasably attached to the electronic apparatus through an existing externally accessed read only data input thereof, to have the capability of not only permitting the reading of data from the accessory control device by the electronic apparatus but also provided with a capability of writing data to the electronic apparatus through the existing externally accessed read only input of the electronic apparatus.
It is a further object of this invention to provide an intelligent cartridge for adapted for releasably attachable employment with existing electronic apparatus, such as page printers, through an existing external inlet, and, when so attached, to improve the operational speed and functionality of the electronic apparatus.
It is a still further object of this invention to releasably attachable accessory control device or cartridge for page printers that is designed to work in conjunction with externally accessed, read only input connector to enhance the image processing throughput to the page print engine.